Control of current flow through the semiconductor body by means of discrete subareas of the semiconductor layers in order to increase the efficiency of the device is often desired in connection with optoelectronic semiconductor devices, in particular luminescence diodes or semiconductor laser devices.
For example, no current should be injected under an electrical connecting contact (bond pad) in a radiation emitting optoelectronic device, because a relatively large part of the electromagnetic radiation that would be created in areas of the active zone under the connecting contact would be absorbed, and could therefore not be emitted from the device.
Restricting the current-flow area of the optoelectronic semiconductor device to a subarea of the semiconductor chip is often also desired in order to achieve increased charge carrier density in this subarea and therefore a shorter switching time for the optoelectronic device.
Known methods of influencing the current path through an optoelectronic semiconductor device are underlying the electrical connecting contact with an insulating layer, implantation of protons in subareas of a semiconductor layer, or selective oxidation of epitaxially produced AlAs layers in order to create current limiting apertures.
However, for semiconductor materials with high transversal conductivity, the effectiveness of underlying the connecting contact with an insulating layer is restricted to areas close to the surface, since the conductivity of the semiconductor itself is not affected. On the other hand, the previously mentioned methods of proton implantation and selective oxidation of AlAs layers can be used to change the conductivity of discrete subareas of a semiconductor layer. These methods are, however, technically relatively complex.